null would only ever be returned if the item couldn't be located within inventory and this would happen immediately.
In this case, derezzing wouldn't work anyway since there is no item to derez.
If delete doesn't occur first then the update thread can outrace the IsAttachment = false necessary to save attachments and send hud artifacts to other viewers.
Serialization of attachments requires IsAttachment = false so that correct positions are serialized instead of avatar position.
However, doing this when a hud is still attached allows race conditions with update threads, resulting in hud artifacts on other viewers.
This change sets SOG.IsDeleted before serialization changes take place (IsDeleted itself is not a serialized property).
LLClientView then screens out any deleted SOGs before sending updates to viewers.
Previously, setting IsAttachment to false then true was necessary to serialize the updated attachment object information.
However, UpdateAttachmentPosition no longer does this update.
Whilst IsAttachment is set to false there is a race condition where the update thread can wrongly send hud object updates to clients that do not own the hud, resulting in screen artifacts.
The reference is not guaranteed to be there when AddRegion() is called but will definitely be present at RegionLoaded() if it's going to be present at all.
This is because the attachments module code was setting the 'object slam' bit by using PermissionMask.All
Solution here is to route the attachment item creation call through the existing inventory code in BasicInventoryAccessModule rather than copy/pasted code in AttachmentsModule itself.
Viewer 2/3 will sometimes attempt to rewear attachments, even though they have already been attached during the main login process.
This change ignores those attempts.
This stops script failures during login, as the rewearing was racing with the script startup code.
It might also help with attachments being abnormally put into deleted state.
Hopefully resolves some more of http://opensimulator.org/mantis/view.php?id=5644
As far as I can see, this is only invoked by a PUT request to ObjectHandlers, which is not being used anyway.
Invoking attachments code at this point is probably inappropriate since it would still be invoked when the client entered the scene.
Being commented to simplify analysis of attachments issues. Can be uncommented when in use.
Also, small tweak to lock and log removal of a SOG from the SceneObjectGroupsByLocalPartID collection in SceneGraph.GetGroupByPrim() if an inconsistency is found.
Attach and detach packets are processed asynchronously when received from a viewer.
Bugs like http://opensimulator.org/mantis/view.php?id=5644 indicate that in some situations (such as attaching/detaching entire folders of objects at once), there are race conditions between these threads.
Since multiple data structures need to be updated on attach/detach, it's not enough to lock the individual collections.
Therefore, this commit introduces a new IScenePresence.AttachmentsSyncLock which add/remove operations lock on.
This was happening because we were using the source avatar's item IDs in the clone appearance.
Switch to using the asset IDs of attachments instead for NPCs.
The InventoryAccessModule and AttachmentModule had to be changed to allow rezzing of an object without an associated inventory item.
Hopefully goes some way towards resolving http://opensimulator.org/mantis/view.php?id=5653
It's never possible for SOG to have no RootPart, except in the first few picosends of the big bang when it's pulled from region persistence or deserialized
The approach here, as in other parts of OpenSim, is to return a copy of the list rather than the attachments list itself
This prevents callers from forgetting to lock the list when they read it, as was happening in various parts of the codebase.
It also improves liveness.
This might improve attachment anomolies when performing region crossings.
Justin Clark-Casey (justincc)